The shale gas revolution has shifted propylene production from naphtha cracking to on-purpose production with propane dehydrogenation (PDH) as the dominant technology^1-9. Because PDH is endothermic and requires high temperatures that favour sintering and coking, the challenge is to develop active and stable catalysts^1-3 that are sufficiently stable^10,11. Zeolite-supported Pt-Sn catalysts have been developed to balance activity, selectivity and stability^12,13, and more recent work documented a PDH catalyst based on zeolite-anchored single rhodium atoms with exceptional performance and stability¹⁴. Here we show for silicalite-1 (S-1) that migration of encapsulated Pt-Sn₂ clusters and hence agglomeration and anchoring within the zeolite versus agglomeration on the external surface can be controlled by adjusting the length of the S-1 crystals’ b-axis. We find that when this axis is longer than 2.00 μm, migration of Pt-Sn₂ monomers during PDH results in intra-crystalline formation of (Pt-Sn₂)₂ dimers that are securely locked in the channels of S-1 and capable of converting pure propane feed to propylene at 550 °C for more than 6 months with 98.3% selectivity at 91% equilibrium conversion. This performance exceeds that of other Pt-based PDH catalysts and approaches that of the Rh-based catalyst. While synthesis requirements and cost are currently prohibitive for industrial use, we anticipate that our approach to controlling the migration and lockup of metals in zeolites may enable to development of other noble metal catalysts that offer extended service lifetimes in industrial applications^15-17.

页岩气革命已将丙烯生产从石脑油裂解转变为以丙烷脱氢 （PDH） 为主导技术的专用生产 ^1-9。由于 PDH 是吸热性的，并且需要有利于烧结和焦化的高温，因此挑战在于开发足够稳定的活性和稳定的催化剂 ^{1-3 10,11}。已经开发了沸石负载的 Pt-Sn 催化剂来平衡活性、选择性和稳定性 ^12,13，最近的工作记录了一种基于沸石锚定单铑原子的 PDH 催化剂，具有卓越的性能和稳定性 ¹⁴。在这里，我们展示了硅石-1 （S-1） 封装的 _{Pt-Sn 2} 团簇的迁移，因此沸石内的团聚和锚定与外表面的团聚可以通过调整 S-1 晶体的 b 轴的长度来控制。我们发现，当该轴长于 2.00 μm 时，PDH 期间 Pt-Sn₂ 单体的迁移导致晶内形成 （Pt-Sn₂）₂ 二聚体，这些二聚体牢固地锁定在 S-1 的通道中，并且能够在 550 °C 下将纯丙烷进料转化为丙烯超过 6 个月，在 91% 平衡转化率下具有 98.3% 的选择性。这种性能超过了其他 Pt 基 PDH 催化剂，并接近 Rh 基催化剂。虽然目前工业用途的合成要求和成本令人望而却步，但我们预计我们控制沸石中金属迁移和锁定的方法可能能够开发其他贵金属催化剂，从而在工业应用中提供更长的使用寿命 ^15-17。